Endocrine Surgery — Extent of Surgery for Papillary Thyroid Carcinoma after Neck Irradiation
A 28-year-old woman presents with a painless left neck swelling. At age 12 she received external beam radiotherapy to the neck for Hodgkin lymphoma. Ultrasound shows a 4 by 3 cm solid nodule confined to the left thyroid lobe, a normal-appearing right lobe and no abnormal cervical lymph nodes. Fine needle aspiration confirms papillary thyroid carcinoma. Which of the following is the most appropriate surgical management?
- A.Total thyroidectomyCorrect
- B.Left lobectomy
- C.Left lobectomy with isthmusectomy
- D.Subtotal thyroidectomy
Explanation
For papillary carcinoma between 1 and 4 cm without extrathyroidal extension or nodal disease, current American Thyroid Association guidance allows either lobectomy or total thyroidectomy, and the choice turns on features that raise the chance of disease in the other lobe or the need for radioiodine. Prior head and neck irradiation is one of those features: radiation-associated cancers are more often multifocal and bilateral, the remaining lobe stays at risk of new tumours, and total thyroidectomy also allows radioiodine and thyroglobulin surveillance. A tumour at the 4 cm upper limit adds weight to the same decision. Lobectomy, with or without the isthmus, is appropriate for a low-risk unifocal cancer of this size in a patient with no radiation history, no family history and a normal contralateral lobe, so it is the closest competitor but is outweighed here. Subtotal thyroidectomy leaves thyroid tissue on both sides, combines the disadvantages of both approaches and complicates any later completion surgery. Cancer larger than 4 cm, gross extrathyroidal extension, or clinically involved nodes or distant metastases make total thyroidectomy mandatory regardless of other factors.
Why each option
- A.
- Correct. A history of neck irradiation increases multifocal and contralateral disease risk, so total thyroidectomy is preferred for this 4 cm cancer.
- B.
- Lobectomy suits low-risk 1 to 4 cm tumours without radiation exposure, but leaves an irradiated contralateral lobe at continuing cancer risk.
- C.
- Adding isthmusectomy does not address the irradiated right lobe, which remains at increased risk of further multifocal carcinoma.
- D.
- Subtotal thyroidectomy leaves bilateral remnants, is inadequate cancer surgery, and makes later completion surgery or radioiodine planning harder.
Reference: 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer (Recommendation 35); UpToDate — Differentiated thyroid cancer: surgical treatment
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